Means for producing ultrashort hertzian waves



Jan. 20, 1942. F. SCHROTER 2,270,479

MEANS FOR PRODUCING ULTRASHORT HERTZIAN WAVES Filed Jan. 25, 1941 Snventor Fritz ,amzzf; 8B M Gttomeg Patented Jan. 20, 1942 UNITED STATES PATENT OFFICE MEANS FOR PRODUCING ULTRASHORT HERTZIAN WAVES poration of Germany Application January 25, 1941, Serial No. 375,931 In Germany November 2, 1938 8 Claims.

The object of this invention is a device adapted to generate feebly damped decimeter and centimeter waves of considerable power. It represents a new development and embodiment of the principle known from Hertzs and Righis time, namely, to discharge a dipole capacity which, upon opening its break, is charged from a highpotential source, by closing the same break, and to repeat this cycle at a frequency as high as possible. What is thus produced are trains of waves the damping of which is not only a function of the radiation resistance of the oscillator, but to an essential extent also of the closing resistance of the break or gap and other losses or dissipative resistances (eddy-currents, dielectric losses). To bridge the break or gap, recourse in the past has been had usually to spark discharge which on charging the dipole halves to flashover potential difference was initiated automatically.

Contradistinct to other arrangements of the same nature known in the earlier art, the embodiment of a wave generator according to the present invention is predicated essentially upon the use of the following novel means, to wit:

(1) Increase of the flashover potential difference of the gap by using unusually high values for the air or gas pressure. Thus, with reduced width of the gap, very appreciable charge potentials and thus large powers of the generator may be obtained.

(2) Periodic closure of the gap by means of a metallic contact, preferably liquid mercury, with the result that the damping component due to the spark decrement is markedly diminished.

(3) Increase in charge frequency of the dipole to extremely high values by resorting to a flow device which per unit of time allows to secure a great number of closings and openings of the gap.

(4) The use of air or other gases highly anhydrated, as high pressure and in a state of speedy flow, for insuring an efficient quench of the opening spark, in combination with the step enumerated in (3).

A more detailed description of the invention follows, in conjunction with a drawing wherein Figs. 1, 2, 3a and 4 illustrate different embodiments of the invention; Figs. 3b and 3c are details of Fig. 3a.

Fig. 1 shows an exemplified embodiment of the invention drawn to an exaggerated scale. Fitted F into the tube or pipe piece R made of insulation material are the dipole halves D and D being of suitable shape. These dipoles are united with the source of high-voltage supply by way of small radio frequency choke-coils S, S", the latter comprising a single turn or a mere bend in a solid wire. If desired, the latter could be iron. The source may furnish either direct current or alternating current. Other inductances or resistances included in the charge circuit have been omitted because unessential to an understanding of the principles involved. Now, through the narrow channel of tube R, a regular sequence of mercury drops 1, 2, 3, etc., is blasted by the aid of a high-pressure perfectly dry air or gas current in the direction of the arrow so that as high a speed of flow results as possible. Such a sequence or train of mercury drops of like size and spaced like intervals apart may be produced in various ways and means, for instance, an aspirator or by the aid of a centrifuge. During the passage of the insulating air column which each time separates two consecutive mercury drops, the oscillator halves D and D" are charged to the potential of the source. As the mercury drops fly through, they become discharged with the generating high frequency in the form of a slightly damped oscillation. Because of the extremely high rate of flow of the air or gas molecules, the spark set up on opening in the gap by rupture of the mercury drop between D and D will at once be efficiently quenched. D and D should be made of a very hard material, say, tungsten or else of non-magnetic nickel-steel non-alloyable with mercury. Their surface in such portions as do not come in contact with mercury may be coated or lined with metal possessing the highest conductivity.

Operating with a device as shown in Fig. 1

" with application of adequately high air pressure so that, for instance, a charge potential of U:50,000 v. is possible, and assuming that the capacity of the oscillator is 0:1 microfarad (centimeter wave range); further, the speed of flow of the air=100 meters per second so that the distance between centers of a pair of mercury drops would be 2.5 cm. it will be seen that the number of charges and discharges per second will be n-4000, while the aggregate power conversion is Inasmuch as the values taken for n and U by no means represent the upper limits of what is attainable, with constant C, it is likely that N may be increased still to a substantial degree. Because of the smallness of C, the ensuing wave length falls inside the centimeter wave-length band.

N 5 watts Fig. 2 illustrates a somewhat modified embodiment of the oscillator in a pressure chamber which at the same time serves as the pool for the mercury for the purpose of conveying it through a closed cycle of circulation. This path includes a device (not shown) which is adapted to circulate the air or the gas current, as well as the division or atomization of the mercury, so as to result in droplets. D, D" again denote the two oscillator halves with the radio frequency choke-coils directly associated therewith, said coils being designed to keep the ensuing ultrahigh frequencies away from the feed leads. I, E 3, 4, etc., denotes various mercury drops. 5 i the volume of mercury which is gathered at the bottom of the chamber. The arrows indicate the direction of circulation. The mercury drops pass at equal distances or intervals through a nozzle being of suitable form and enter the gap between the two oscillator halves D, D. Also, the cross-section of said gap should be suitably chosen in order that snug and intimate adhesion between the mercury and the metallic contacts may be promoted, and that breaking up of the drop, thumping or rebounding and other disturbing actions may be avoided. Built into the collector chamber are one or several screens or shields designed to guard the oscillatory system against untimely and inadvertent short-circuits by sputtering of mercury.

Figs. 3a to 30, inclusive, illustrate other embodiments of the basic idea of this invention. In this form of construction, one oscillator half, for the purpose of minimizing wear and tear as well as the load, has been replaced by a plurality of cyclically alternating structures of the same sort, while of the other oscillator half there is just one unit, and this one unit has a special design and form, This system is capable of operating either with a sequence of mercury drops being insulated from one another in a way as shown in Figs. 1 and 2, or with an uninterrupted mercury thread or column exuding jet-fashion under application of suitable pressure. The various oscillator halves D I, D'2, D'3 Dn are seated equi-spaced, upon the periphery of a rotating support of non-conducting material of circular disk shape, as indicated at K. These units are united by way of radio frequency choke-coils S l, 3'2, 8'3, S'n with an axial high-potential supply lead. A represents the metallic rotation shaft of the support K which is fed with charge current by way of a slip ring. To each and all of the moving or rotor oscillator halves is coordinated jointly a static conductor of reduced dimensions D to represent the second or complementary oscillator half, It forms at the same time the metallic mouthpiece of nozzle R whence the mercury stream issues. The connection between D" and the source of charge current includes a radio frequency choke-coil As shown in Fig. 3c. the nozzle is positioned obliquely in reference to'the axis of rotation of the disk K in order that portions of mercury which are refiected may be urged into the desired direction where they are harmless, as indicated by the arrow H in order that thus disturbing spatter effects by droplets may be avoided.

The instant the drop of mercury issuing from the mouthpiece of the nozzle touches one of the charged oscillator halves as they fly along, an oscillatory discharge takes place in the closed dipole. The opening spark which immediately will be set up will be rapidly ruptured and quenched as a result of the high tangential velocity of the rotor part. This quenching eliect will be still further promoted because of the fact that this embodiment is predicated upon working with a stream of mercury drops being brokenup by air columns of suitable length, but then care must be taken so that the number of oscillator halves flying past the nozzles D" per unit of time will be the same as the number of mercury drops issued, and such issuance must be in phase. The air current which follows each drop will thus be caused to blast through the intervening space between the various dipole halves D'l, DZ, etc., and promote the immediate quenching of the breaking or opening spark. The whole process, of course, occurs inside a chamber in which there is a very high air or gas pressure in order that sufficiently high fiashover potentials may be obtained.

It will be evident that the arrangements hereinbefore described are capable of a great many modifications. For instance, the mercury drops issuing from nozzle R in Figs. 3a and 30 could themselves be made to play the part of an oscillator half D" provided it is caused to make conductive connection with the corresponding pole of the source of charge energy at the proper instant. It is, moreover, conceivable to mount the positively charged dipole parts, as in Fig. 3b, upon one circular disk, and a similar number of negatively charged dipole members upon another, similar circular disk, both disks being thereupon revolved in opposite directions in the plane of revolution, the intervening space being chosen so that the rims of the oscillator plates almost touch. A jet of mercury blasted through the narrow clearance or air-gap between both dipole rims, either uninterrupted or else broken up at the proper phase relations, will then periodically produce the short-circuit each time resulting in the oscillation of the oscillable individual system. Also, this arrangement could be operated inside a high-pressure ambient or atmosphere,

Among other feasible embodiments of the invention will next be described an arrangement by reference to Fig. 4 of the appended drawing which is quite plausible. Two jets Hg+ and Hgconsisting of insulated metallic drops, separated by air or gas bubbles, with the said metal drops being caused to assume potential differences and charges as high as possible by passing current supply leads of contrary polarity, shortly after, issue from directional metallic nozzles R, R" at a suitable angle of intersection with the result that in the open space they clash with great kinetic energy. Incidentally, the charges become equalized in oscillatory form. Because of the fact that the oscillator halves in the form of droplets may be diminished in size to a great extent, this makes it feasible to obtain especially short waves of little damping. The suction of the directionally flowing air which may be still further accelerated and promoted by an ad-- ditional air or gas current Z, aids the approaching of the droplets, but at the same time any premature spark-like break of the discharge will be counteracted by the violent stream of the gas molecules, in other words, rapid conveyance or abduction of charge carriers is largely counteracted. The problem of preventing or of the rapid extinction or quenching of opening sparks is absent in this embodiment, and this constitutes a great technical advantage.

The high charge potential of the oscillator halves, for instance, may be produced by highpotential rectifier assemblies of well-known type,

though it could be produced also by generators of the kind predicated upon the production of friction or influence electricity. If this, in the last-named instance, is insured by high-speed rotational machines, these could be constructionally united quite easily with the embodiment illustrated in Figs. 3a to 30. Charge and oscillation generator in that case constitute a joint construction unit.

In all of the exemplified embodiments of the invention hereinbefore described, one decisive point is to impart to the flow of metallic drops or particles extremely high velocities, for it is only in this way that the converted energy is increasable to the desired levels, with a short building up period for a sufliciently low-resistance bridge or path between the halves constituting the oscillator. In the old method of flashover by sparks, the time interval for the decline of the resistance from an infinite value down to a moderate ohm figure is of an order of magnitude of 1 seconds. Inside this period of time, with centimeter waves and the resultant spark decrements the oscillation has practically died out and decayed (10 periods for a wave-length of 3 cm.). Hence, the problem arises to abbreviate the building up period of an equally good or higher conductivity than possessed and offered by the spark to an appreciable extent in comparison with the said conditions. requires extremely fast bridging of the oscillator halves by the front or face of the entering metal drops. It is likely that in an arrangement as here disclosed, the air sheath surrounding the metal drop acts like an extremely thin-walled insulator which causes the electrostatic field, after the flying metal mass has entered the gap between the oscillator halves, to be crowded together to a well nigh infinite area, thereby allowing punctures through the gas film that are practically timeless. However, these punctures or breakdowns develop only after the active surface of the confined dielectric, and thus the number of breakdown chances have grown sufficiently great But the situation may also be so in number. that, at the first instant a purely metallic connection is established between the oscillator halves, this connection, of course, being of a very high resistance, and throughout the said connection minute metal particles are caused to vaporize, with the result that a speedy ionization is created in the entire bridging space.

In some of the exemplified embodiments of the invention as before described, say, Figs. 3a to 30 and 4, it is possible to use solid metallic globules or particles, say, spherules of silver or ferronickel in lieu of liquid metal or mercury, which, when clashing with the oppositely charged conductor part become discharged.

This condition What is claimed is:

1. The method of producing oscillations which includes charging with opposite potentials two portions of a radiating system by means of separate charging elements, disconnecting said two portions from their respective charging elements, and bringing said portions together in contact with each other.

2. The method of producing oscillations which includes separately charging with opposite potentials two portions of a radiating system, and projecting said portions to meet at a remote point where the charges are dissipated in oscillatory fashion.

3. An oscillation generator comprising a pair of spaced nozzles whose ends are directed toward a common point, means for charging said nozzles at opposite relative polarities, and means for projecting through said nozzles a flow of discrete metal particles with sufiicient force to cause the particles from said nozzles to meet at said common point.

4. An oscillation generator comprising a pair of spaced hollow metallic tubes angularly disposed relative to each other so that a continuation thereof would cause them to intersect at a common point, a source of potential for maintaining said tubes at opposite relative polarities, means for projecting separated metallic particles through said tubes toward said common point, and means for directing a flow of gaseous fluid toward said common point in a direction away from said hollow tubes.

5. An oscillation generator comprising a pair of spaced nozzles whose ends are directed toward a common point, means for charging said nozzles at opposite relative polarities, means for projecting through said nozzles a flow of liquid metal drops with suflicient force to cause the particles from said nozzles to meet at said common point, and a nozzle for directing a flow of gas toward said common point in a direction away from said first nozzles.

6. The method of producing oscillations which comprises charging particles with potentials of opposite polarities relative to ground and projecting them toward each other to cause them to meet at a common point.

'7. The method of producing oscillations which comprises projecting toward each other particles charged with opposite polarity relative to ground to cause them to meet at a common point.

8. The method of producing oscillations which comprises projecting toward each other particles charged with different potentials to cause them to meet at a common point.

FRITZ SCI-IROTER. 

